OSX/libsecurity_filedb/lib/OverUnderflowCheck.h

   1 #ifndef __OVERUNDERFLOWCHECK__
   2 #define __OVERUNDERFLOWCHECK__
   3
   4 inline uint32 CheckUInt32Add(uint32 a, uint32 b)
   5 {
   6         uint32 c = a + b;
   7         if (c < a)
   8         {
   9                 CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  10         }
  11
  12         return c;
  13 }
  14
  15
  16
  17 inline uint32 CheckUInt32Subtract(uint32 a, uint32 b)
  18 {
  19         if (a < b)
  20         {
  21                 CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  22         }
  23
  24         return a - b;
  25 }
  26
  27
  28
  29 inline uint32 CheckUInt32Multiply(uint32 a, uint32 b)
  30 {
  31         uint32 c = a * b;
  32         uint64 cc = ((uint64) a) * ((uint64) b);
  33         if (c != cc)
  34         {
  35                 CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  36         }
  37
  38         return c;
  39 }
  40
  41
  42
  43 inline uint64 Check64BitAdd(uint64 a, uint64 b)
  44 {
  45         uint64 c = a + b;
  46         if (c < a)
  47         {
  48                 CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  49         }
  50
  51         return c;
  52 }
  53
  54
  55
  56 inline uint64 Check64BitSubtract(uint64 a, uint64 b)
  57 {
  58         if (a < b)
  59         {
  60                 CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  61         }
  62
  63         return a - b;
  64 }
  65
  66
  67
  68 inline uint64 Check64BitMultiply(uint64 a, uint64 b)
  69 {
  70         if (a != 0)
  71         {
  72                 uint64 max = (uint64) -1;
  73                 uint64 limit = max / a;
  74                 if (b > limit)
  75                 {
  76                         CssmError::throwMe(CSSMERR_DL_DATABASE_CORRUPT);
  77                 }
  78         }
  79
  80         return a * b;
  81 }
  82
  83
  84
  85 #endif